This invention relates to vehicle guidance means for use, in the most important example, with tractors and other agricultural vehicles.
A vehicle guidance system has been proposed in published European application No. 68626 which employs a laser on the vehicle to direct a laser beam along the direction of motion of the vehicle towards a target which carries beam reversing means and is positioned on the vehicle path so as to direct the beam back to the vehicle. The returned beam can, it is suggested, be detected visually by the vehicle driver or electronically with photo-electric cells or the like driving a display which is energized when the vehicle is on course, that is to say heading towards the target. The quoted specification further suggests the use of two electronic detectors positioned one each side of the beam path to enable an indication to be given on whether the vehicle is departing from its course to the left or to the right, thus giving the sense of the required steering correction. The two detectors can be used to drive a display indicating LEFT, ON COURSE or RIGHT. Alternatively, the input of the detectors can--in the case of a driverless vehicle--be coupled to means controlling the direction of motion of the vehicle.